Support & maintenance

This page describes how to troubleshoot and repair a Heliomotion tracker of the latest model (Tracker Z). For earlier models see the legacy support page.


The software tool Heliocom is used to communicate with the tracker for service purposes. To use it, launch the program on a Windows laptop and connect it to the USB terminal on the tracker’s circuit board using the USB cable provided (Type-A Male to Type-A Male).

Program download: Heliocom v0.98A
Program description: Heliocom manual

If Heliocom is unable to connect then you need to restart the tracker first, by toggling its power off until the LED lights turn off. After connecting following a restart, you can press the stop button twice and wait a few seconds to stop GPS sync as well as pause automatic tracking.

The circuit board has five LEDs that indicate the status of the tracker:

  • Green (A) – Blinks to indicate that the tracker is powered and operational.
  • Yellow (B) – Lit if the tracker has paused its operation due to being unable to rotate. Blinks to indicate movement to either start or noon position.
  • Orange (C) – Lit to indicate temperature alarm (for thermal installations). Blinks instead of green LED to indicate the clock battery is depleted.
  • Blue (D) – Lit during GPS synchronization, which occurs at startup and dawn.
  • Red (E) – Lit to indicate satellites were not found during the latest GPS synchronization.

A second set of two LEDs are found near the bottom of the circuit board: red and orange. The orange led is lit while the motor is running. The red led is not used.

The Heliomotion tracker’s operation is fully automatic. When powered on the tracker goes through the following steps to track the sun:

  1. The tracker waits until a GPS fix has been established to retrieve information needed to calculate the sun’s current position: latitude, longitude, date and time. This information is recalibrated every morning.
  2. The tracker rotates to face the sun’s present position.
  3. As the sun moves across the sky the tracker follows it, moving in intervals of 1.8 degrees every couple of minutes. After each movement the tracker positions itself 0.9 degrees ahead of the sun.
  4. The tracker continues to follow the sun until sunset or until its evening position is reached, which is 90 degrees after the noon position.
  5. After sunset the tracker returns to its noon position.
  6. Before sunrise the tracker moves to sunrise position or to morning position, which is 90 degrees before the noon position.
  7. The tracker awaits sunrise and then repeats the sequence from Step 4.

If a Heliomotion installation is left without power the wind may eventually rotate the framework to morning or evening position. The end stops will physically prevent the tracker from rotating far beyond these positions.

If the tracker encounters an obstacle that prevents it from rotating the tracker will pause its normal operation before trying to rotate again. The motor power is set to a low value (5 Nm) by default for safety reasons, allowing a person or obstacle to easily stop the rotation of the tracker without causing damage to the installation or injuries to any person. The default rotation speed is also set low (5 minutes for 180 degrees) for safety reasons. Parameters such as “Motor Power” and “Motor Speed” can be adjusted using the Heliocom software.

The “Service Count” and “Service Timeout” parameters visible in Heliocom are used for obstacle handling. Every time the tracker completes a rotation it updates the Position value to its new calculated position and checks the Sensor’s value to make sure it is within “Sensor Margin” degrees from its calculated Position. If the Sensor value deviates too far from the Position value, the tracker updates the Position value to the value read from the Sensor and increments an error counter.

The tracker then retries the rotation. If the tracker fails consecutively “Service Count” number of times, the tracker will pause its operation for “Service Timeout” number of minutes, going into service mode. Each time service mode is entered the Service Timeout is increased by 60 minutes up to 6 times (reset every morning).


Solutions (in green) are described in detail lower down on this page.

Solutions (in green) are described in detail lower down on this page.
For common sources of friction please view this PDF.

Update to the latest Firmware version (v60 or later) to solve this issue.

Some GPS modules sometimes give an incorrect date value (January 1st) when the daily GPS synchronization is performed in the morning. When this happens the tracker moves to the morning position later than usual (calculating sunrise time as if it’s January 1st) before the date is automatically corrected by another morning GPS synchronization taking place. See Updating Firmware solution for details on how to solve this.

Check for and remove any obstacles that can hinder rotation to morning/evening positions, such as snow or vegetation.

Also check that the end stops are positioned correctly so as to not interfere with regular 180 degree rotation. The end stops are a safety feature to physically prevent the tracker from rotating beyond the morning/evening positions.

End stop

There should be a small (2-3mm) distance from the end stop and the fork arm when tracker is in morning/evening position.


A replacement External Gear can be ordered using the Contact form.

Replace the gear as described below.

  1. Pull down the Drive Cover by first unscrewing three M4 bolts underneath the Drive Cover and four M4 bolts on the sides of the cover. Be careful not to drop any bolts. Tool: 2.5mm hex key (Allen wrench).
  2. Turn off the power to the tracker (preferably) so it doesn’t rotate when external gear/motor/sensor is not attached.
  3. Use a plier to cut the cable tie used for shortening the Motor’s wires.
  4. Unscrew the four M4 bolts attaching the Motor to the Front Plate and place the Motor on top of the Drive Cover. Tool: 3mm hex key.
  5. Take out the new External Gear so it is ready for use.
  6. Unscrew the four bolts connecting the Front Plate to the Back Plate of the external gearbox.
  7. Pull the Front Plate away sufficiently to remove the previous External Gear. Be careful so the plastic bushings do not fall away.
  8. Attach the new External Gear to the Position Sensor’s shaft first, and then attach it to the Slew Drive’s shaft. If the External Gear is a tight fit, use a plastic hammer to tap it all the way onto the shaft (some slew drive shafts are slightly larger than normal).
  9. Reattach the four screws holding the Front Plate to the Back Plate, making sure the External Gear is correctly attached on both sides.
  10. Make sure the Front Plate is not pressing against the External Gear, causing needless friction, by pushing the gear (~1mm) further onto the slew drive shaft using your hand (or two small screwdrivers if more force is needed).
  11. Reattach the Motor with four bolts, making sure the motor shaft goes into the slot in the Back Plate.
  12. If the External Gear’s attachment to the Slew Drive is broken the tracker will not rotate but the Position Sensor will rotate. Therefore, if the External Gear is changed after it has been worn out the Position Sensor will then need to be recalibrated. Perform the “Basic Calibration” steps as described in the “Calibrating Position Sensor” section of this page.
  13. Reattach the Drive Cover with its seven bolts.
  14. Turn the power to the tracker back on.
  15. The metal gear has slightly more friction than the plastic gear. Therefore it is recommended to increase Motor Power setting from 110 to 120 (+20% torque). See “Changing Motor Torque” section.

To calibrate the Position Sensor connect a laptop to the tracker via Heliocom (see Using Heliocom section). Make sure the Drive Cover is pulled down so that the Position Sensor is accessible.

Heliocom displays two positional values: “Position” and “Sensor”. The unit for these values is in degrees relative to midday (noon) position (0.0), so morning position is -90.0 degrees and evening position is 90.0 degrees. Position is the calculated position the tracker relies on mainly, whereas Sensor is the value read from the Position Sensor that the tracker uses to check that it completes its rotations successfully.

There are three main parameters shown in Heliocom used for calibrating the Position Sensor: Position Noon, Position Morning, Position Evening. These specify the raw value read from the Position Sensor (0-1023) when moving clockwise to these three positions. They are used by the tracker to map what rotational position correspond to what sensor value (-90 to +90 degrees). There is also the Sensor Gap parameter that specifies the sensor lag in degrees when switching from clockwise to counter-clockwise rotation (typically 0.0-2.0 degrees).

The Position Sensor parameters have been factory calibrated. Therefore, only a Basic Calibration has to be performed when a worn out External Gear is replaced (and only if the gear is worn out where it attaches to Slew Drive). If on the other hand the Position Sensor or the Circuit Board have been replaced then the Full Calibration needs to be performed.

Basic Calibration

  1. Use Heliocom to rotate the tracker until the Sensor value in Heliocom shows ~0.0 degrees after moving clockwise. So if for instance the sensor shows 10.0 degrees, then first move 15 degrees counter-clockwise and then 0.5 degrees at a time clockwise repeatedly until ~0.0 degrees is reached (this is done to avoid any potential sensor lag). This value must be close to the middle (512) of the sensor interval, specifically within 470-540, so that the sensor doesn’t go past its valid range in the morning or evening position.
  2. Remove the three screws holding the Position Sensor and then carefully unmount the Position Sensor from the External Gear while maintaining the worm gear’s position with your finger so that the worm gear doesn’t rotate (as that would change the position of the sensor).
  3. Use Heliocom to rotate the tracker to midday position (where the angle rod and the balk are aligned).
  4. Reattach the Position Sensor without changing its position more than necessary for reattaching it.
  5. Use Heliocom to rotate the tracker 5 degrees counter-clockwise and then 5 degrees clockwise to confirm that the Sensor is close to 0.0 degrees (plus/minus 1 degree) while the tracker is aligned to midday position.
  6. Reattach the Drive Cover and restart the tracker (Restart button in Heliocom or toggle power) to switch it back to automatic tracking mode.

Full Calibration

  1. Perform all steps of the Basic Recalibration, but leave the tracker stopped in exact midday position.
  2. Click on the “Test” button in Heliocom. Heliocom will automatically rotate to the morning position, then evening position and then back to the midday position. The recommended sensor parameters for Morning, Noon and Evening Position will be displayed in Heliocom when the test concludes (takes about 10 minutes). Manually update to these recommended values to fully calibrate the sensor.
  3. The Position Sensor is now calibrated and you can press the “Restart” button in Heliocom to have the tracker resume automatic tracking mode.

If the Position Sensor does not function correctly or is damaged a replacement Sensor can be ordered via the Contact Form.

The firmware of the solar tracker can be updated using the USB connection and Heliocom. The firmware version can be seen when connected to the tracker using Heliocom, ex “v4650-58” means version 58 is installed. Note, this firmware update cannot be used with earlier models (Tracker S and Tracker XL). These models can be upgraded to the new circuit board.

To update the firmware download and unzip the following software:
Heliocom: Heliocom
Bootloader: Bootloader
Heliofirmware: Heliofirmware v62
Log: Software update log

1. Run Heliocom and the Bootloader (HIDBootloader.exe) on a laptop. Heliocom is used to communicate with the tracker and the Bootloader is used to update the firmware.

2. Unscrew the lid to the tracker’s circuit board using the screwdriver.

3. Connect the USB cable from the laptop to the USB port on the circuit board. Heliocom will then automatically connect to the tracker.

4. The solar tracker has four unique settings used for calibrating its Position Sensor. Please make a note of these unique values seen in Heliocom: Position Noon, Position Morning, Position Evening, and Sensor Gap. These settings will need to be manually restored after the update is complete since they will be overridden with default values.

5. In Heliocom, click the ”Boot” button and the tracker will disconnect from Heliocom and instead connect to the Bootloader application.

6. In the Bootloader application, click the open icon to the left of the top menu. Browse and open the latest firmware (.hex file) for the tracker that was downloaded and unzipped earlier.

7. Click the ”Erase/Progam/Verify Device” button (second from the left) to perform the firmware update. If the update would fail for any reason restart the Bootloader and try the firmware update again.

8. When the update is complete click the ”Reset” button to the right of the menu to restart the tracker which disconnects from the bootloader and reconnect to Heliocom. Note that the version number seen in Heliocom will now have changed to read “v4650-61”.

9. In Heliocom, click 2 times consecutively on the ”Stop” button and wait a couple of seconds for the tracker to stop. The first click aborts the automatic GPS synchronization performed at startup and the second click pauses automatic tracking.

10. Change the four settings written down earlier: Position Noon, Position Morning, Position Evening, and Sensor Gap. To change a setting first click the ”Edit” button next to that setting. The field then becomes editable and the button changes name to “Set”. Type the new value into the field and click the “Set” button to submit the new setting to the tracker. Do this for all four unique parameters.

11. Click on the ”Restart” button in Heliocom to allow the tracker to resume normal operation.

12. Disconnect the USB cable and put the lid back on the box.

The motor power setting can be changed with Heliocom if more or less motor torque is needed. Default setting is “120” (previously 110) which translates to 24 watt at Motor Speed 3. Motor power setting translates to power output as follows: 90 = 10W, 100 = 15W, 110 = 20W, 120 = 24W, 130 = 26W, 140 = 30W, 150 = 35W, 160 = 39W. Note that the default included transformer is rated for max 30W.

If motor power is insufficient the motor will give of a sound as it’s unable to rotate the motor shaft. If the motor power is set too high (>160) motor driver on the circuit board will not allow the motor to run until the power setting is reduced, preventing damage to the motor.

Motor strength can also be increased by raising the operation voltage of the circuit board, by turning the voltage adjustment potentiometer on the 24VDC transformer clockwise. Allowed voltage range of circuit board is 10-29 VDC. Adjusting the transformer from 24 VDC to 29 VDC will increase the motor strength linearly by 20%.

You should also look through the checklist in the “Friction and Imbalance” section in case any of those issues are interfering with the rotation.

As a redundancy feature the tracker is equipped with a replaceable clock module which includes a backup battery (3V lithium cell). Should the GPS module or GPS network fail the tracker can still keep operating for many years using this clock and the stored latitude/longitude settings. Note that the tracker operates on solar time, which is different from local time. The sun always reaches its highest elevation at 12:00 solar time.

The clock module is located here on the circuit board:

If the battery is depleted the orange LED on the circuit board blinks instead of the green LED.

The tracker will continue working even after the battery depletes. It is a redundancy in case the GPS module fails in which case the tracker will rely solely on the timekeeping of the clock module.

The clock module used is a standard “DS3231 RTC Clock Module for Raspberry PI”.

A replacement clock module can be purchased from for instance AliExpress.

Turn off power to the tracker when replacing the RTC module. When restarted the tracker will automatically update the clock settings from GPS data and use the new module for timekeeping.

If the GPS module does not manage to synchronize to the GPS network the red LED on the circuit board is lit. The tracker can continue working for years even if the GPS module fails as it will then rely solely on the clock module for time keeping. However, the time keeping of the clock module will gradually go out of sync over the years and so a faulty GPS module should be replaced.

The GPS module is plug-and-play. Just remove the faulty module from its pins on the circuit board and plug in the new one.

A replacement GPS module can be ordered by contacting us via the Contact Form.

The tracker can be powered by any 24 VDC transformer able to provide at least 1.5A of current. The transformer supplied with the installation is the DIN-rail mounted Mean Well HDR-30-24. Make certain to turn off all AC and DC power to the distribution box before replacing the transformer.

A replacement 24VDC transformer can be purchased for instance from AliExpress.

Turn off power to the tracker before changing the circuit board. Make sure each wire is connected to the correct screw terminal as shown in the picture below before turning the power back on again.

A replacement circuit board can be ordered via the Contact Form.

Specify the unique serial number of the tracker (seen on a label inside of the circuit board box, ex “Z19200”) and we will supply the circuit board with factory settings for your tracker (otherwise sensor calibration will be necessary).

Friction or an imbalance of the framework may make it needlessly difficult for the tracker to rotate the framework. Check the list below for possible causes.

Panel balance
Make sure the panels are balanced in the middle of the angle brackets as shown in the picture below. Microinverters mounted on the lower half of the framework do not cause an imbalance issue, but if the panels are significantly off center the motor will have difficulty rotating the framework.

Rod support
Make sure the rod support plate (circled in red) is oriented as shown in the picture below. If it is oriented towards the balk the fork joint cannot rotate properly and it will be difficult for the tracker to rotate.

Angle bracket orientation
The angle brackets (marked in red) need to be oriented as shown in the picture below. If they are rotated the other way around the balance point will be way off and it will be 5 times more difficult for the tracker to rotate.

M16 bolts
The two M16 bolts (circled in red) should not be tightened so much as to cause friction. They should only barely touch the M16 nylon washer. You can loosen the fork joint and tilt the framework up and down to make sure there is no resistance from the M16 bolts being screwed on too tightly.

24V transformer
Use a voltage meter to confirm that the 24V transformer delivers close to 24VDC, even while the motor is running. The 24V voltage can be measured on the screw terminal circled in red below. If the voltage falls significantly during motor rotation the transformer needs to be replaced. If the voltage falls to for instance 12V the motor torque will be halved.

Fork joints
Make sure the two fork joints (F) are unscrewed at least half a turn to allow for full 180 degree range of motion. The clevis eye (E) also rotates slightly, so it too needs to be unscrewed half a turn so as to not interfere with the rotation.

It is recommended to apply long-life grease to the threads of the clevis eye (E) and the fork joints (F) as well as to the rotating shaft that locks the clevis eye to the fork joint. This reduces friction which can otherwise cause noise to occur during rotation. Depending on weather, this process may need to be repeated every couple of years to keep friction low.

Slew drive
If the cause of the friction appears to come from the slew drive go through the following procedures.

  1. Detach the angle rod (threaded M16 rod) and strap the framework down horizontally. Then attempt to rotate the tracker manually using Heliocom to determine if the source of the friction actually comes from the slew drive. During factory test the slew drive is rotated with 2 watt (motor setting 40) to make sure there are no needless friction in the gears. An assembled PV-6 requires about 8 watt (motor setting 80) to rotate reliably (when there’s no wind). The default setting is 24 watt (motor setting 120). If the drive rotates fine when the angle rod is detached check for any imbalances or friction areas around the angle rod’s attachment points before reattaching the angle rod. A significant imbalance over a number of weeks may potentially cause the slew drive gears to become jammed or have increased friction due to a lack of grease. Remove the imbalance to avoid this happening.
  2. Remove the drive cover, motor and front plate so that the external gear attached to the slew drive is exposed. Try rotating the slew drive by turning the external gear by hand. Rotating the gear by hand towards morning/evening position should be easy. Rotating the gear towards midday position should be harder, but still doable with one hand. If this is possible without much effort then the friction is caused by the front metal plate pushing against the external gear too hard. Add 4x M4 nylon washers as extra bushings when reassembling the external gearbox.
  3. If the gear cannot be rotated by hand then remove the gear and try turning the slew drive shaft using a pipe wrench or similar tool. If this managed to unjam the drive the reassemble the external gearbox. Detach the angle rod (threaded M16 rod) and check for any significant imbalance when tilting the panels.
  4. If the drive is not jammed but appears to have an increased internal friction then it needs to be relubricated through its grease nipple(s). Slew drives are supplied fully lubricated but if they are strained they may need to be relubricated after a number of years in service. Recommended grease, according to manufacturer, is listed below.
  5. Insert grease using a grease gun, then rotate the drive via Heliocom between morning and evening position (90 degrees at a time) to spread the grease around the drive. Repeat until friction is removed or until grease starts coming out of the bearings (indicating that the drive is full and does not need any more greasing).
  6. If drive friction is not lowered despite relubricating the drive then remove the framework, rotate the drive 180 degrees via Heliocom and then reassemble the framework. This way the drive uses the previously unused gears which has no wear on them.
  7. If none of these solutions work then replace the drive unit.


It is recommended to apply long-life grease to the threads of the clevis eye (E) and the fork joints (F) as well as to the rotating shaft that locks the clevis eye to the fork joint. This reduces friction which can otherwise cause noise to occur during rotation. Depending on weather, this process may need to be repeated every couple of years to keep friction low.